A new study has brought the concept of male contraception a step closer to reality.
Scientists at the University of Sydney carried out a review of 30 studies involving 1,756 men between the ages of 18 and 51 and concluded that a combination of testosterone - the primary male sex hormone - and progestin - a synthetic form of progesterone - was particularly promising.
According to a report of the study in the Journal of Clinical Endocrinology & Metabolism, the hormone combination suppressed sperm production faster and more effectively than testosterone alone.
Lead author and associate professor Peter Liu revealed that the rate of sperm output suppression is "comparable to that achieved after a vasectomy".
"It is possible to suppress sperm output to concentrations that are comparable with reliable contraception in most, but not all men," he added.
The researchers noted that it was difficult to predict which men will respond best to the hormone treatment but Professor Liu emphasised that "considerable progress" had been made.